This study is concerned with the effects of glucocorticoids on several surface-related phenomena in human cells of malignant derivation. The emphasis is placed on differences in response to these steroids between lymphoid cells whose growth is inhibited by glucocorticoids and the epithelioid cells which show a partial phenotypic reversal toward an ordered type of cell growth. On the biochemical level the investigation includes studies of the biosynthetic pathways leading from mevalonate to its various products. In addition an attempt is made to correlate glycolipid and glycoprotein composition of treated cells with different types of responses to glucocorticoids.